We propose to continue our research efforts on the cerebral metabolic responses to hypoglycemia in perinatal animals. Previous investigations in our laboratory have demonstrated that lactic acid can substitute as a cerebral fuel for glucose during hypoglycemia in newborn dogs. Further studies have revealed that perinatal animals tolerate the combined metabolic stresses of hypoglycemia and hypoxia far less well than either insult alone. The metabolic consequences of hypoglycemia superimposed on hypoxia relate to a reduced glycolytic capacity as well as an earlier exhaustion of high-energy phosphate reserves in brain than during hypoxia alone. Future research endeavors will include 1) the establishment in hypoglycemic newborn animals of the hypoxic treshold below which cerebral metabolic disturbances occur, 2) the determination of residual acute and long-term cerebral consequences of hypoglycemia combined with hypoxia and 3) a study of the role played by hyperglycemia in the pathogenesis of hypoxic brain damage.